FUNCTIONAL MATRIX HYPOTHESIS- REVISITED

PRESENTED BY SUSNA PAUL

CONTENTS

• FUNCTIONAL MATRIX THEORY- ORIGINAL

• FUNCTIONAL MATRIX HYPOTHESIS- REVISITED ROLE OF MECHANOTRANSDUCTION ROLE OF AN OSSEOUS CONNECTED CELLULAR NETWORK GENOMIC THESIS EPIGENETIC ANTITHESIS & RESOLVING SYNTHESIS

• REFERENCES

FUNCTIONAL MATRIX THEORY(1960s)

• The concept of this theory was introduced first by Vander Klaaw (1948-52).

• Melvin L. Moss developed the functional matrix hypothesis.

The craniofacial skeleton develops initially and later grows in direct response to the extrinsic epigenetic environment..

BONES DO NOT GROW ,THEY ARE GROWN

DEFINITION

The origin, form, position, growth and maintenance of all skeletal tissues and organs are always secondary, compensatory and necessary responses to chronologically and morphologically prior events or processes that occur in specifically related nonskeletal tissues, organs or functioning spaces (functional matrices).

ExplanationThe FMH considers the head, not the skull as a composite

area of individual encapsulate areas..

Totality of skeletal structure+ soft tissue+ functioning space

Functional Cranial Component

FUNCTIONAL CRANIAL COMPONENT

SKELETAL UNIT FUNCTIONAL MATRIX

MICRO MACRO PERIOSTEAL

CAPSULAR

SKELETAL UNIT

MICRO SKELETAL• Skeletal units may be composed variably of bone, cartilage

or tendinous tissues. • When a bone consists of a number of skeletal units, we call

them micro skeletal units..

MACRO SKELETAL• When adjoining portions of a number of neighboring bones are

united to function as a single cranial component, we term this as a macro-skeletal unit.

• eg: endocranial surface of the calvaria

THE FUNCTIONAL MATRIXTHE PERIOSTEAL MATRIX

This corresponds to the immediate local environment, which acts directly..

Egs: muscles, blood vessels, nerves, glands, teeth..

• The periosteal matrices stimulation causes direct growth of the microskeletal units.

• Effect on the size and/or shape of the skeletal unit by osseous deposition and resorption.

TRANSFORMATION

THE CAPSULAR MATRIX

Defined as the organ and spaces that occupy a broader anatomical complex.

Each capsule is an envelope - contain a series of FCC - skeletal unit and the related functional matrices..

Sandwiched between two covering layers

OROFACIAL CAPSULEIn this, the cover consists of skin and mucous membrane.

The orofacial capsule surrounds and protects the orofacial functional matrix..

The volumetric expansion of the orophoryngeal functioning spaces

Increase in the size of the capsule

The whole of the included and enclosed functional components, are translated to a new position in space.

NEUROCRANIAL CAPSULE

• In this, the cover consists of skin and duramater.

• The neuro-cranial capsule surrounds and protects the neurocranial functional matrix..

The expansion of the enclosed capsular matrix volume.

The capsule enlarges

The whole of the included and enclosed functional components, are

carried outward in a totally passive manner.

• Thus the capsular matrices acts indirectly on the macroskeletal units and are carried outward in a passive manner.

• The location in space of the skeletal unit is changed, not by osseous deposition and resorption.

TRANSLATION

FUNCTIONAL CRANIAL COMPLEX

GROWTH

TRANSLATION

TRANSFORMATION

CAPSULAR MATRIX

PERIOSTEAL MATRIX

MACROSKELETON

MICROSKELETON

SKELETAL UNITFUNCTIONAL MATRIX

CONSTRAINTS OF THE FMH

1. Methodologic constraint: Macroscopic measurements which use the techniques of point mechanics and arbitrary reference frames.

Roentgenographic cephalometry permitted only method specific descriptions that cannot be structurally detailed. This constraint was removed..

2. Hierarchical constraint:

This version’s descriptions did not extend “downward” to processes at the cellular, subcellular or molecular structural domains or extend

“upwards” to the multicellular process by which bone tissues respond to lower level signals.

1.Mechanotransduction occurs in single bone cells.

2.Bone cells are computational elements that function multicellularly as a connected cellular network.

.

MECHANO TRANSDUCTION

All vital cells are irritable and respond to alterations in their external environment.

1. Mechanoreception 2. Mechanotransduction

Osseous Mechanotransduction

1.Unlike other mechanosensory cells ,bone cell are not specialized for such stimuli

2.These cells shows aneural transmission of signals.

3. Bone loading stimulus evoke three adaptational responses.

4. The changes brought about by stimuli are confined to a single bone to which the signal is transduced.

Translates the information content of a periosteal functional matrix stimulus into a skeletal unit cell signal

MECHANOTRANSDUCTION

Ionic / electricalMechanical

Stretch Activated channel

Activation of plasma membrane stretch activated ion channels

Intra cellular electric events

Electromechanical Involves the osteocytic plasma membrane.

it contains voltage activated ion channels and transmembrane ion flow..

Electrokinetic

Bound and unbound electrical charges, associated with the bone fluids.

Electrical effects in the fluid filled bone are electrokinetic i.e. streaming potential.

MECHANICAL PROCESS

This is an alternate means by which functional matrix may regulate the lower cell bone cell.

The physical continuity of the transmembrane molecule integrin

MECHANORECEPTION

MECHANOTRANSDUCTION

IONIC MECHANICAL

STRETCH ACTIVATED CHANNELS INTEGRIN

ELECTRIC EVENTS

ELECTROMECHANICAL ELECTROKINETIC

CONNECTED CELLULAR NETWORK

All bone cells, expect osteoclasts are extensively interconnected by gap junctions.

Present laterally and vertically.

.

Superficial osteoblast Superficial osteoblast

Periosteal and endosteal osteoblasts

Periosteal and endosteal osteoblasts

Preosteoblastic cellPreosteoblastic cell

CONNECTED CELLULAR NETWORK

• Network theory Initial layer cells –stimuli (loading)

summation

Intracellular signal (mechanotransduction)

Hidden layer cells (adj. Osteocytes)

Final layer cells (osteoblasts) output

The CCNs show oscillation, i.e. reciprocal signaling (feedback) between layers.

Gap junctions are electrical synapses that permit bi-directional signal traffic

ionic transport through the bone cell plasma membrane

intercellular transmission are computed by the operation of an osseous connected cellular network

bone responses

• explanatory chain extending from the

epigenetic event of skeletal muscle contraction, hierarchically downward (through the cellular and molecular levels to the bone cell genome and then) upwards again through histologic levels to the event of gross bone form adaptational changes.

The revised FMH consist of the presentation of, a thesis and an anti-thesis and of a resolving synthesis.

GENOMIC THESIS

• The genomic thesis holds that the genome, from the moment of fertilization, contains all the information necessary to regulate..

• Genomic thesis claims that prenatal cranio facial development is controlled by two inter related processes:

1. Initial regulatory (Homeobox) gene activity.2 Activity of the regulatory molecular groups: growth factor families

and steroid/thyroid family.

EPIGENETIC ANTITHESIS

The genomic thesis passes directly from molecules to morphogenesis: directly from DNA molecules to adult morphology, ignoring the

roles of the many epigenetic processes and mechanism.

The epigenetic antithesis detailing the processes and mechanisms seeking to clarify the casual chain between genome & phenotype.

• Process Series of action or operation that had towards a particular result.

• Mechanism Fundamental physical or chemical process(es) involved in, or responsible for an action, reaction or other nailed phenomenon

Epigenetics refers to the entire series of interactions among cells and cell products, which leads to morphogenesis and differentiation..

A RESOLVING SYNTHESIS

• Morphogenesis is regulated (controlled, caused) by the activity of both genomic and epigenetic processes and mechanisms.

REFERENCES

• The functional matrix revisited.1. The role of mechanotransduction. AJODO –1997 ; 112 :8-11.

• The functional matrix revisted 2. The role of an osseous connected cellular network AJODO -1997; 112:221-6

• The functional matrix revisited.3 .The genomic thesis AJODO-1997;112:338-42

• The functional matrix revisited.4 .The epigenetic antithesis AJODO-1997;112:410-7